The bass control on the Euphoria isn't like a standard bass control on other pedals, such as what you'd find on an EQ pedal for example. The pedal doesn't cut bass like a tubescreamer type circuit does, so neutral is with the knob all the way down. As you turn up the bass you'll notice it gets a little more hair on the notes... almost like a fuzz will but not quite as raspy as a fuzz.
More info on the pedal here https://wamplerpedals.com/products/euphoria